Five-Zone Heart Rate Training Calculator

How it is calculated

Maximum heart rate is taken from your input or, if the field is empty or 0, estimated as 220 − age. The five zones are 50–60, 60–70, 70–80, 80–90 and 90–100 %. With the Karvonen method each boundary is resting + (max − resting) × p / 100, so the zones are percentages of heart-rate reserve. With the max-HR method it is simply max × p / 100 and the resting rate is not used in the result. All values are beats per minute (bpm), rounded to whole numbers. Neighbouring zones share a boundary value, so a pulse right on the edge belongs to either. Inputs that cannot be real show no result: an age above 120, a resting rate outside 25–130 bpm, a typed maximum above 250 bpm, or a maximum that does not exceed the resting rate.

Common mistakes

• Comparing zones from the two methods as if they were the same. For a 55 bpm resting rate, Zone 1 is 120–133 bpm by reserve but 93–111 bpm by percent of max.
• Expecting the resting rate to change the max-HR result. In that mode only the maximum matters.
• Using the 220 − age estimate as a lab-tested figure. If you know your real maximum from an all-out test, enter it; the zones shift with it (190 instead of 185 moves Zone 1 to 123–136 bpm).
• Entering a resting rate taken after exercise or caffeine. It raises the bottom of every zone in the reserve method, and a value above 130 bpm is rejected outright.
• Reading the zone limits as hard walls. Zones touch (133 ends zone 1 and starts zone 2), and watch readings fluctuate by a few beats.